Aminoplast resin/thermoplastic polyamide presize coatings for abrasive article backings

ABSTRACT

The present invention provides a composition for use in coated abrasives. The curable composition comprises a mixture of: i) from about 30 to about 60 weight percent of an oligomeric aminoplast resin having on average at least one pendant α,β-unsaturated carbonyl group per oligomeric unit; ii) from about 70 to about 40 weight percent of a thermoplastic polyamide miscible in said aminoplast resin, the weight percents being based on the total resin content; and iii) a sufficient amount of a catalyst for the curable oligomeric aminoplast resin having on average at least one pendant α,β-unsaturated carbonyl group per oligomeric unit, said catalyst being stable at a temperature of mixing of the components. The curable composition can either be in the form of a melt-processable solid or a molten mixture. The present invention also provides single and multilayered treated backing substrates used in coated abrasives.

BACKGROUND OF THE INVENTION

[0001] This invention relates to coating compositions for abrasivebackings and particularly to those compositions containing an aminoplastresin and a thermoplastic resin.

[0002] Coated abrasives generally comprise a flexible backing upon whicha binder holds and supports a coating of abrasive grains. The backingcan be selected from paper, cloth, film, vulcanized fiber, etc., or acombination of one or more of these materials. The abrasive grains canbe formed of flint, garnet, aluminum oxide, alumina-zirconia, ceramicaluminum oxide, diamond, silicon carbide, and the like. Binders arecommonly selected from phenolic resins, hide glue, urea-formaldehyderesins, urethane resins, epoxy resins, and varnish. Phenolic resinsinclude those of the phenol-aldehyde type.

[0003] Coated abrasives may employ a make coat of resinous bindermaterial in order to secure the abrasive grains to the backing, and asize coat of resinous binder material can be applied over the make coatand abrasive grains in order to more firmly bond the abrasive grains tothe backing. The resinous material of the make and size coats may be thesame material or may be different materials. A common resinous materialused for both make and size coatings is generically referred to asphenolic resin. Phenolic resins are a class of materials made from thereaction of phenol with various aldehydes.

[0004] Phenolic resins are commonly used in coated abrasive articlesbecause of their high adhesive strength to abrasive particles,durability, and high thermal stability. There are two types of phenolicresins, resole and novolac. Resole phenolic resins have a molar ratio offormaldehyde to phenol greater than or equal to one to one, typicallybetween 1.5:1.0 to 3.0: 1.0. Novolac resins have a molar ratio offormaldehyde to phenol less than one to one.

[0005] The phenolic resins contain about 70 percent to about 85 percentsolids, and preferably contain about 72 percent to about 82 percentsolids. If the percent solids are very low, then more energy is requiredto remove the water and/or solvent. If the percent solids is very high,then the viscosity of the resulting phenolic resin is too high whichleads to processing problems. The remainder of the phenolic resin ispreferably water with substantially no organic solvent due toenvironmental concerns with the manufacturing of abrasive articles.Examples of commercially available phenolic resins include those knownunder the trade designations VARCUM and DUREZ, available from OccidentalChemical Corp., Tonawanda, N.Y.; AROFENE and AROTAP, available fromAshland Chemical Company, Columbus, Ohio; RESINOX, available fromMonsanto, St. Louis, Mo.; and BAKELITE, available from Union Carbide,Danbury, Conn.

[0006] Although phenolic resins are widely used in the coated abrasivesindustry, phenolic resins do not adhere well to some types of backingmaterials. Poor adhesion may cause the phenolic binder to peel away orshear off prematurely as the abrasive article is subjected to normaluse. This lack of adhesion limits the types of backings that can be usedin coated abrasive articles that use phenolic resin binders.

SUMMARY OF THE INVENTION

[0007] In one aspect, the invention provides a treated substrate for anabrasive article. The treatment coat, also called a “presize” is madefrom a binder precursor or curable composition comprising an oligomericaminoplast resin having on average at least one pendant α,β-unsaturatedcarbonyl group per oligomeric unit, a thermoplastic polyamide, and acatalyst for crosslinking or curing the α,β-unsaturated functionality ofthe aminoplast resin.

[0008] In another aspect, the invention provides a substrate for anabrasive article comprising a) a backing; and b) a crosslinked treatmentcoat on said backing, said treatment coat is formed from a curableprecursor composition comprising a mixture of i) from about 30 to about60 weight percent of an oligomeric aminoplast resin having on average atleast one pendant α,β-unsaturated carbonyl group per oligomeric unit,ii) from about 70 to about 40 weight percent of a thermoplasticpolyamide miscible in said aminoplast resin, the weight percents beingbased on the total resin content, and iii) a sufficient amount of acatalyst for the curable oligomeric aminoplast resin having on averageat least one pendant α,β-unsaturated carbonyl group per oligomeric unit,said catalyst being stable at the temperature of mixing of thecomponents.

[0009] In another aspect, the invention provides a curable precursorcomposition comprising a) from about 30 to about 60 weight percent of anoligomeric aminoplast resin having on average at least one pendantα,β-unsaturated carbonyl group per oligomeric unit; b) from about 70 toabout 40 weight percent of a thermoplastic polyamide miscible in saidaminoplast resin, the weight percents being based on the total resincontent; and c) a sufficient amount of a catalyst for the curableoligomeric aminoplast resin having on average at least one pendantα,β-unsaturated carbonyl group per oligomeric unit, said catalyst beingstable at temperature of mixing of the components.

[0010] The cured composition is also useful as a make coat, a size coatfor coated abrasives, and as a laminating adhesive for multi-layerbacking substrates.

[0011] In another aspect, the invention provides a treated substratecomprising a substrate which comprises a hydroenhanced cloth and atreatment coat on the substrate. “Hydroenhanced” means that thesubstrate is treated using high pressure water to increase the surfacearea of the yarns. An example of this treatment is described in U.S.Pat. No. 4,976,456. The treatment coat may be selected from a variety ofcompositions suitable for use in abrasive articles.

[0012] The term “precursor” means the binder is uncured and notcrosslinked. The term “crosslinked” means a material having polymericsections that are interconnected through chemical bonds (that is,interchain links) to form a three-dimensional molecular network. Thus,the binder precursor is in an uncured state when applied to the backing.

[0013] In general, the aminoplast resin/polyamide treatment coatcomprises a semi-interpenetrating polymer network of a cured orcrosslinked thermosetting polymer and a thermoplastic polymer. As usedherein, a “semi-interpenetrating polymer network (semi-IPN)” is definedas a polymer network of two or more polymers wherein at least onepolymer is crosslinked and at least one is uncrosslinked.

[0014] For purposes of this application, “cured,” “crosslinked,” and“polymerized” can be used interchangeably. For purposes of thisinvention, a binder precursor is “energy-curable” in the sense that itcan crosslink (that is, cures) upon exposure to radiation; for example,actinic radiation, electron beam radiation, and/or thermal radiation. Abinder precursor may be in the form of a molten mixture or may be asolid at room temperature. For instance, a binder precursor may be asolid film that is transfer coated to the backing. Upon heating toelevated temperatures, this binder precursor is capable of flowing,increasing the tack of the hot melt binder precursor, and allowing thehot melt binder precursor to penetrate and bond intimately with thebacking substrate. Alternatively, for instance, if the resin issolvent-borne (organic or water), (<100 percent solids) or blended withlow molecular weight reactive diluents (100 percent solids), the binderprecursor may be liquid at room temperature.

[0015] As used herein, a “hot melt”composition refers to a compositionthat is a solid at room temperature (about 20 to 22° C.) but which, uponheating, melts to a viscous liquid that can be readily applied to abacking. A “melt processable” composition refers to a composition thatcan transform, for example, by heat and/or pressure, from a solid to aviscous liquid by melting, at which point it can be readily applied to abacking.

[0016] Desirably, the aminoplast resin/polyamide binder precursors ofthe invention can solid state). However, if so desired, it may befeasible to incorporate solvent or other viscosity-reducing reactivediluents into the binder precursor.

[0017] A “cloth” is a generic term which includes all textile fabrics orfelts. A “cloth” as used herein, may contain any of the commonly knowntextile fibers, natural or manmade, or a combination thereof, and whichare formed by weaving, knitting, felting, needling, or other processesknown in the textile industry.

[0018] A “continuous filament yarn” is a yarn comprising indefinitelylong fibers such as those found in silk, or those manufactured fiberswhich are extruded into filaments and then assembled into a yarn with orwithout a twist.

[0019] The aminoplast resin/polyamide compositions of the inventioncombine the toughness, the improved adhesion to other resins such asphenolics, and the melt-processibilty of thermoplastic polyamides withthe rapid curing, high temperature stability, and phenolic resincompatibility of the oligomeric aminoplast resins. The resultingsolventless compositions are processed at moderate temperatures(220-260° F. (104-127° C.)) as compared with typical thermoplasticmaterials processed in excess of 204° C., and thus allow the use oftemperature sensitive backing materials in coated abrasives. Theaminoplast resin/polyamide compositions of the invention may also beused as laminating or transfer coating adhesives in composite backingsthat provide strength and durability similar to that of cloth at lesscost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] A preferred binder precursor of the invention contains from about20 to about 60 weight percent of an oligomeric aminoplast resin havingon average at least one pendant α,β-unsaturated carbonyl group peroligomeric unit and from about 40 to about 80 weight percent ofthermoplastic polyamide, the weight percent being based on the totalresin content of the composition. A more preferred binder precursor ofthe invention contains from about 30 to about 40 weight percent of anoligomeric aminoplast resin having on average at least one pendantα,β-unsaturated carbonyl group per oligomeric unit and from about 60 toabout 70 weight percent of thermoplastic polyamide, the weight percentbeing based on the total resin content of the composition. A preferredcatalyst for the oligomeric aminoplast resins is a free radicalproducing photoinitiator. The preferred aminoplast resins of theinvention are acrylamidomethyl-novolac resins (AMNs).

[0021] The binder precursors of the invention preferably contain atleast one oligomeric aminoplast resin having on average at least onependant α,β-unsaturated carbonyl group per oligomeric unit. Aminoplastresins having at least one pendant α,β-unsaturated carbonyl group peroligomeric unit are made by reacting an amino compound with an aldehyde;the resulting product is then reacted with an oligomeric material.Formaldehyde is the preferred aldehyde.

Aminoplast Resins

[0022] The preferred oligomeric material is a phenol novolac resin.Typically, the phenol novolac resin is made by reacting a phenol monomerwith an aldehyde in the presence of an acid catalyst, with the molarratio of the aldehyde to phenol being less than one. Examples ofaldehydes used to prepare novolacs include formaldehyde, acetaldehyde,propionaldehyde, glyoxal, and furfural. The preferred aldehyde isformaldehyde because of its availability, reactivity, and low cost. Atypical phenol novolac resin is illustrated below:

[0023] There are essentially no hydroxymethyl groups present for furthercondensation. Typically, these materials have a molecular weight rangingfrom about 300 to about 1,500. Additionally, the starting phenol monomercan be substituted with various groups such as alkyl, alkoxy, carboxyl,and sulfonic acid, so long as there are at least two reactive sitesremaining to form the novolac.

[0024] Instead of using the phenol monomer, other chemicals can bereacted with the aldehyde to produce a novolac type resin. Examples ofthese chemicals include: cresol, xylenol, resorcinol, catechol,bisphenol A, naphthols, or combinations thereof to form a novolac resin.

[0025] To form the oligomeric aminoplast resins of this invention, theaminoplast having hydroxyalkyl groups and the oligomeric material arefirst combined in a reaction vessel along with an acid catalyst.Representative examples of acid catalysts include trifluoroacetic acid,p-toluenesulfonic acid, and sulfuric acid. Then, the reaction mixture isgently heated to about 30° to 100° C., preferably 70° to 80° C. to bringabout any one of the following reactions:

[0026] where R¹ is as defined above; R⁴ represents a substituent, orcombination of substituents, that does not adversely affect thereaction; R⁵ represents —OH, —SH, —NH₂, hydrogen, alkylamnino group,alkylthio group, alkyl group, or alkoxy group; R⁶ represents anα,β-unsaturated alkenyl group. The alkylamino, alkylthio, alkyl, alkoxyand alkenyl groups of R⁵ and R⁶, preferably have 1 to 20 carbon atoms,inclusive. Examples of substituents suitable for R⁴ include hydrogen,alkyl group, preferably having 1 to 20 carbon atoms, inclusive, alkoxygroup, preferably having 1 to 20 carbon atoms, inclusive, —OH group,mercapto group, and other groups that activate the aromatic ring towardelectrophilic substitution. These types of reactions are commonlyreferred to as Tscherniac-Einhorn reactions.

[0027] There may be side reactions and other products formed fromReactions I through III.

[0028] Examples of the type of reaction encompassed by Reaction IV canbe found in the following references: Zaugg, H. E.; W. B. Martin,“Alpha-Amido alkylations at Carbon”, Organic Reactions, Vol. 14, 1965pages 52 to 77; and Hellmann, H., “Amidomethylation”, Newer Methods ofPreparative Organic Chemistry, Vol. II, Academic Press (New York andLondon; 1963), pp. 277-302, both of which are incorporated herein byreference.

[0029] In Reactions I through III, the first reactant is a typicalexample of an oligomeric material. In the reactants in Reactions Ithrough III, n is preferably an integer between 0 and 8, because on bothsides of the n group there is a monomeric repeating unit. Thus, whenthese two monomeric repeating units are added to n, the total number ofrepeating units is between 2 and 10. Specific compounds and details oftheir manufacture are found in U.S. Pat. No. 5,236,472, the contents ofwhich are incorporated herein by reference.

[0030] A preferred oligomeric aminoplast resin having on average atleast one pendant α,β-unsaturated carbonyl group per oligomeric unit isan acrylamidomethyl-novolak resin or AMN. Useful AMNs of the inventionhave an average acrylamide functionality of from 0.8 to 2.5 acrylamidegroups per aromatic ring. Preferred AMNs of the invention include thosehaving an average acrylamide functionality of 1.5-2.0 acrylamide groupsper aromatic ring. An even more preferred AMN has an average acrylamidefunctionality of 1.5 acrylamide groups per aromatic ring. Useful AMNs ofthe invention have a formaldehyde to phenol ratio (F/P) of from 0.25 to1.0. The preferred F/P ratio for the AMNs of the invention is 0.5 on amolar basis. The F/P ratio is the molar ratio of formaldehyde to phenolcharged in the reactor.

Thermoplastic Polyamides

[0031] Compositions of the invention also contain at least onethermoplastic polyamide. The thermoplastic polyamides of the inventionare compatible with the oligomeric aminoplast resins in the melt phase.“Compatible” means that the oligomeric aminoplast resin and thethermoplastic polyamide are sufficiently miscible and the meltviscocities of the oligomeric aminoplast resin and the thermoplasticpolyamide are sufficiently similar such that a uniform mixture can beobtained with conventional extrusion compounding equipment. Thethermoplastic polyamides of the invention have melting points that arelower than the thermal reaction temperature of the oligomeric aminoplastresins. The melting points of the thermoplastic polyamides are below thetemperature required to initiate crosslinking of the oligomericaminoplast resins. Useful thermoplastic polyamides of the invention havea melting point temperature in the range of about 95 to about 150° C. asmeasured by differential scanning calorimetry (DSC). Preferredthermoplastic polyamides of the invention have a DSC melting point ofabout 95 to about 110° C., and a more preferred thermoplastic polyamidehas a melting point of about 103° C.

[0032] The viscocities of the polyamides of the invention are similar tothose of the oligomeric aminoplast resins of the invention at theprocessing temperature of the oligomeric aminoplast resin (about 104 -127° C.) Useful thermoplastic polyamides of the invention have a meltflow rate of about 10 to 90 g/10 min, preferably about 15 to 90 g/10min, more preferably about 50 to 90 g/10 min, and even more preferablyabout 90 g/10 min, at a temperature of 160° C.

[0033] Preferred thermoplastic polyamides are terpolymers produced fromlactams and diamines. Preferred polyamides are made from lauryl lactamas one of the monomers. Preferred commercially available thermoplasticpolyamides are terpolymers produced from lactams and diamines. Thepreferred commercially available thermoplastic polyamides have the tradedesignations VESTAMELT 732, VESTAMELT 730, VESTAMELT 742, VESTAMELT750/751, VESTAMELT 755, and VESTAMELT 760, and are available fromCreanova, Somerset, N.J.

Catalysts

[0034] The compositions of the invention contain at least one catalystfor curing the oligomeric aminoplast resin. The oligomeric aminoplastresin can be cured by heat or radiation energy. If the oligomericaminoplast resin is cured by heat, the temperature of the oven should beset to at least about 120° C. and held at this temperature for at least4 hours. Curing can be effected in shorter times at higher temperatures.The temperature requirements may be lower depending upon the heatstability of the synthetic or paper backings.

[0035] If the oligomeric aminoplast resin is cured by radiation, theamount of radiation depends upon the degree of cure desired of theoligomeric aminoplast resin used in the binder. Examples of radiationenergy sources include ionizing radiation, ultraviolet radiation, andvisible light radiation. Ionizing radiation preferably has an energylevel of 0.1 to 10 megarad, more preferably 1 to 10 megarad. Ultravioletradiation is electromagnetic radiation having a wavelength of from about200 to 400 nanometers. Visible light radiation is electromagneticradiation having a wavelength of from about 400 to 760 nanometers. Therate of curing of the binder composition depends upon the thickness aswell as the optical density and nature of the composition.

[0036] If the oligomeric aminoplast resin is cured by heat, a thermalinitiator can be utilized to facilitate and/or enhance the rate orextent of cure. Examples of useful thermal initiators include peroxides,for example, benzoyl peroxide, azo compounds, benzophenones, andquinones.

[0037] If the binder precursor composition is to be cured by ultravioletradiation, a photoiniator is required to initiate free radicals.Examples of such photoinitiators include organic peroxides, azocompounds, quinones, benzophenones, nitro compounds, acyl halides,hydrazones, mercapto compounds, pyrylium compounds, triacrylimidizoles,bisimidizoles, chloroalkyltriazines, benzoin ethers, benzil ketals,thioxanthones, and acetophenone derivatives. Useful commerciallyavailable photocatalysts or photoinitiators include those under thetrade designation IRGACURE having product numbers 369, 651, and 961, allavailable from Ciba Geigy Chemicals, Hawthorne, N.Y.

[0038] If the binder precursor composition is to be cured by visiblelight radiation, a photoinitiator is required to initiate free radicalpolymerization. Examples of useful visible light photoinitiators can befound in U.S. Pat. No. 4,735,632. Preferably the catalysts are activatedby photochemical means.

Optional Components

[0039] Optionally, the aminoplast resin/polyamide binder precursorcompositions of the invention can further comprise anacrylamidomethyl-phenol resin (AMP). Preferably, the AMP would have arelatively low molecular weight (less than 500), an acrylamidefunctionality sufficient to provide crosslinking, and sufficientmiscibility and viscosity with the oligomeric aminoplast resin and thepolyamide so to form a compatible mixture as defined above. SpecificAMPs and details of their manufacture are found in U.S. Pat. No.4,903,440, the contents of which are incorporated herein by reference.

[0040] Any known and compatible additive useful in coatings in theabrasives art may be used as long as the amount of the additive useddoes not adversely affect the performance characteristics of the end-useproduct or article. Common additives include optically transparentfillers such as feldspar and silica, slip agents, and materials usefulfor dissipating static charges such as carbon black and graphite.

Backings

[0041] Useful backings of the invention may be comprised of cloth,vulcanized fiber, paper, nonwoven materials, fibrous reinforcedthermoplastic backing, polymeric films, substrates containing hookedstems, looped fabrics, metal foils, mesh, foam backings, and transfercoated multilayer combinations thereof and are of the appropriate weightfor the end use application.

[0042] The raw backings can be provided as woven fabrics using yarnscomposed of natural or synthetic fibers, as polymeric films, or aslaminates of different types of polymeric materials, or as laminates ofpolymeric materials with non-polymeric materials. The woven polymericfabrics may have different yarns in the warp and weft directions.

[0043] Cloth backings can be porous or sealed and they may be woven orstitch bonded. The cloth backing materials may also be surface treatedusing high pressure water (hydroenhanced) as described in U.S. Pat. No.4,967,456, incorporated herein by reference. The effect of the watertreatment is to increase the surface area of the yarns which provides acloth that more readily and uniformly absorbs the desired chemicalcomposition. Such cloths have a uniform surface finish and improvedcharacteristics such as cover, abrasion resistance, drape, and reducedair permeability. The cloth backings may include fibers or yarns ofcotton, polyester, rayon, lyocell, silk, nylon, or blends thereof. Theyarns may be made of continuous filaments. The cloth backings can beprovided as laminates with different backing materials described herein.

[0044] Examples of useful commercially available cloth backing materialsinclude polyester fabrics woven with either spun yarns or continuousfilament yarns, available from Milliken, Spartansburg, S.C.; andhydroenhanced polyester fabrics, available from Interspan Division ofBBA Nonwovens, Fort Mill, S.C.

[0045] Paper backings can also be barrier coated, backsized, untreated,or fiber-reinforced. The paper backings also can be provided aslaminates with a different type of backing material.

[0046] Nonwoven backings include spunbonded webs and laminates todifferent backing materials mentioned herein. Laminates may includethose constructions having a network of filaments adhesively bonded ormelt bonded to a nonwoven web. The nonwovens may be formed of cellulosicfibers, synthetic fibers, or blends thereof. Examples of commerciallyavailable nonwoven backing materials include TYPAR spunbondedpolypropylene and REEMAY spunbonded polyester, available fromTypar/Reemay, Old Hickory, Tenn., and STABILON scrims, available fromMilliken. A “scrim” is defined as a fabric with an open constructionused as a base fabric in the production of coated or laminatedsubstrates.

[0047] The foam backing may be a natural sponge material or polyurethanefoam and the like. The foam backing also can be laminated to a differenttype of backing material. The mesh backings can be made of polymeric ormetal open-weave scrims. Additionally, the backing may be a splicelessbelt such as that disclosed in U.S. Pat. No. 5,609,706, or a reinforcedthermoplastic backing that is disclosed in U.S. Pat. No. 5,417,726, bothincorporated by reference herein.

[0048] Preferred backing materials for use in the coated backings of theinvention include cloth backings such as those woven from polyester,cotton, polyester/cotton, rayon, or lyocell yarns.

Preparation

[0049] The aminoplast resin/polyamide binder precursor may be preparedby mixing the various ingredients in a suitable vessel at an elevatedtemperature sufficient to liquefy the materials so that they may beefficiently mixed with stirring, but without thermally degrading them,until the components are thoroughly melt blended. This temperaturedepends in part upon the particular chemistry. For example, thistemperature may range from about 30 to 150° C., typically 50 to 140° C.,and preferably ranges from 90 to 125° C. The components may be addedsimultaneously or sequentially, although it is preferred to first blendthe oligomeric aminoplast resin and the thermoplastic polyamidecomponent. Then, the catalysts are added followed by any optionaladditives including fillers. The binder precursor should be compatiblein the uncured, melt phase. That is, there should preferably be novisible gross phase separation among the components before curing isinitiated.

[0050] The aminoplast resin/polyamide binder precursor may be useddirectly after melt blending or may be packaged in pails, drums, orother suitable containers, as a solid or a powder, preferably in theabsence of light, until ready for use. The binder precursors so packagedmay be delivered to a hot melt applicator system with the use of pailunloaders, block melters equipped with rotating screws, and other solidsfeeding equipment. Alternatively, the hot melt binder precursors of theinvention may be delivered to conventional bulk hot melt applicator anddispenser systems in the form of sticks, pellets, slugs, blocks,pillows, or billets. It is also feasible to incorporate organic solventinto the binder precursor; although this may not always be preferred.

[0051] It is also possible to provide the hot melt aminoplastresin/polyamide binder precursors of the invention as uncured,unsupported rolls of adhesive film. In this instance, the binderprecursor is extruded, cast, or coated to form the film. Such films areuseful in transfer coating the binder precursor to an abrasive articlebacking. It is desirable to roll up the film with a release liner (forexample, silicone-coated Kraft paper), with subsequent packaging in abag or other container that is not transparent to actinic radiation.

[0052] The hot melt binder precursors of the invention may be applied tothe abrasive article backing by extrusion, gravure printing, coating,(for example, by using a coating die, a heated knife blade coater, aroll coater, a curtain coater, or a reverse roll coater), or transfercoating. When applying by any of these methods, it is preferred that thebinder precursor be applied at a temperature of about 80 to 140° C.,more preferably from about 100 to 125° C.

[0053] The hot melt aminoplast resin/polyamide binder precursors can besupplied as free standing, unsupported films that can be transfer coatedto the backing and, if necessary, die cut to a predefined shape beforetransfer coating. Transfer coating temperatures and pressures areselected so as to minimize both degradation of the backing and bleedthrough of the binder precursor and may range from room temperature toabout 120° C. and about 30 to 1000 psi (0.3 to 1 kPa). A typical profileis to transfer coat at room temperature and about 400 - 500 psi (0.4 to0.5 kPa). Transfer coating is a particularly preferred applicationmethod for use with highly porous backings.

[0054] It is also within the scope of this invention to coat theaminoplast resin/polyamide binder precursor as a 100 percent solidsliquid, or from a solvent, although this method is not always preferred.A liquid binder precursor can be applied to the backing by anyconventional technique such as roll coating, spray coating, die coating,knife coating, and the like. After coating the resulting binderprecursor, it may be exposed to an energy source to activate thecatalyst before the abrasive grains are embedded into the binderprecursor. Alternatively, the abrasive grains may be coated immediatelyafter the binder precursor is coated before partial cure is effected.

[0055] The coating weight of the hot melt aminoplast resin/polyamidebinder precursor of the invention can vary depending on the grade of theabrasive particles to be used. In general, the application rate of thebinder precursor composition of this invention (on a solvent free basis)is between about 4 to 500 g/m², preferably between about 20 to about 300g/m².

[0056] Preferably, the hot melt aminoplast resin/polyamide binderprecursor is applied to the abrasive article backing by any of themethods described above, and once so applied is exposed to an actinic,preferably UV, energy source to initiate at least partial cure of thephotosensitive materials. The partial curing facilitates furtherprocessing, web handling, and prevents the coated side of the backingfrom sticking to the backside of the backing when the coated backing isin the form of a roll. Final cure may be completed by further processingwith an additional energy source, typically thermal energy.

[0057] Curing of the hot melt aminoplast resin/polyamide binderprecursor begins upon exposure of the binder precursor to an appropriateenergy source and continues for a period of time thereafter. The energysource is selected for the desired processing conditions and toappropriately activate the chosen photoactive catalyst system. Theenergy may be actinic (for example, radiation having a wavelength in theultraviolet or visible region of the spectrum), accelerated particles(for example, electron beam radiation), or thermal (for example, heat orinfrared radiation). Preferably, the energy is actinic radiation.

[0058] Suitable sources of actinic radiation include mercury, xenon,carbon arc, tungsten filament lamps, sunlight, and so forth. Ultravioletradiation, especially from a medium pressure mercury arc lamp, ispreferred. Exposure times may be from less than about 1 second to 10minutes or more (to preferably provide a total energy exposure fromabout 0.1 to about 10 Joule/square centimeter (J/cm²) depending uponboth the amount and the type of reactants involved, the energy source,web speed, the distance from the energy source, and the thickness of thebinder precursor to be cured.

[0059] The aminoplast resins/polyamide binder precursors may also becured by exposure to electron beam radiation. The dosage necessary isgenerally from less than 1 megarad to 100 megarads or more. The rate ofcuring may tend to increase with increasing amounts of photocatalystand/or photoinitiator at a given energy exposure or by use of electronbeam energy with no photoinitiator. The rate of curing also tend toincrease with increased energy intensity.

Treated Hydroenhanced Backing Substrates

[0060] The present invention also provides treated backing substratescomprising a backing comprising hydroenhanced cloth and a treatment coaton said backing. The type of cloth that may be hydroenhanced is notlimited and may be any type of cloth having the properties required forapplication in an abrasive article. Such properties include sufficientweight, texture, density, weave, heat, and chemical resistance, etc.Preferred hydroenhanced cloths include those made from polyester,cotton, lyocell, rayon, and polycotton yarns. More preferredhydroenhanced cloths are made from polyester yarns.

[0061] The type of treatment coat used on hydroenhanced cloth backingsubstrates is not limited. The treatment coats may be melt processable,or solvent borne, waterborne or 100 percent solids, and radiation orheat curable. Useful treatment coats for the hydroenhanced backingsubstrate include those comprising phenolic resins, novolak resins,nitrile latex resins, aminoplast resins having pendant, α,β-unsaturatedcarbonyl groups, urethane resins, epoxy resins, urea-aldehyde resins,isocyanurate resins, melamine-aldehyde resins, acrylate resins,acrylated isocyanurate resins, acrylated urethane resins, acrylatedepoxy resins, bismaleimide resins, polyester resins, and aminoplastresin/thermoplastic polyamide blends as described herein, acrylatedoligomer/thermoplastic polyamide blends (as described in copending andco-assigned application Ser. No. ____________, filed concurrentlyherewith, Attorney Docket No. 54530USA7A entitled “AcrylatedOligomer/Thermoplastic Polyamide Presize Coatings for Abrasive ArticleBackings,” incorporated by reference herein, and mixtures thereof.Preferred treatment coatings comprise melt processable aminoplastresin/thermoplastic polyamide blends and phenolic resins.

[0062] The treatment coats for the hydroenhanced backing substrate mayalso contain a catalyst, photoiniator, or thermal initiator as describedabove and is known in the art. Such treatment coats may also containother known and conventional additives such as solvents, fillers,viscosity modifiers, and the like.

[0063] The treated hydroenhanced substrates may be prepared by methodslisted above and other known conventional methods. The range of coatingweights for the treatment coat is the same as described above for theaminoplast resin/polyamide compositions. The treated backing substratescan be used alone or may be a layer in a multilayer substrate made bytransfer coating or other known means.

[0064] Hydroenhanced cloth backing substrates provide surprisinglyimproved adhesion to treatment coats and greatly improved flexibilitywhen compared to non-hydroenhanced cloth of the same type.

[0065] Objects and advantages of this invention are further illustratedby the following examples, but the particular materials and amountsthereof recited in these examples, as well as other conditions anddetails, should not be construed to unduly limit this invention.

EXAMPLES

[0066] All parts, percentages, ratios etc., in the examples are byweight unless otherwise indicated. The following designations are usedthroughout the examples:

Glossary

[0067] AMN 1.5 and 2.0 acrylamidomethyl-novolak resin (1.5 and 2.0 moleof N-methylolacrylamide/mole of aromatic ring in the resin) madeaccording to the procedure of U.S. Pat. No. 5,236,472, Preparation C,incorporated herein by reference

[0068] AMP acrylamidomethyl-phenolic resin made according to theprocedure of U.S. Pat. No. 4,903,440, Preparation 4

[0069] CB Carbon black

[0070] CD-1010 cationic triaryl sulfonium salt photoinitiator, availablefrom Sartomer under the designation CD-1010

[0071] DVE-3 a vinyl ether monomer available from ISP Co, Wayne, N.J.,under the trade designation RAPICURE DVE-3

[0072] EP1 a bisphenol A epoxy resin, available from Shell Chemical,Houston Tex., under the trade designation EPON 828 and having an epoxyequivalent weight of 185-192 g/eq

[0073] E-826 Amine curing agent available from Shell Chemical, Houston,Tex. under the trade designation EPICURE 826

[0074] FE203 Iron oxide filler

[0075] H-1581 46 percent solids acrylonitrile latex available from B.F.Goodrich, under the trade designation, HYCAR 1581

[0076] I-651 2,2-dimethoxy-2-phenyl acetophenone photoinitiator,available from Ciba Geigy, under the trade designation IRGACURE 651

[0077] NR-9030 40 percent solids waterborne urethane dispersionavailable from Zeneca Resins, Wilmington, Mass., under the tradedesignation NEOREZ R-9030

[0078] PETA pentaerythritol triacrylate, SARTOMER SR 444, available fromSartomer, Exton, Pa.

[0079] RP-1 a resole phenolic resin having 75 percent solids(non-volatiles)

[0080] RP2 a resole phenolic resin having 76 percent solids(non-volatile).

[0081] RP3 a resole phenolic having 55 percent solids (non-volatile)

[0082] TATHEIC triacrylate of tris(hydroxyethyl) isocyanurate, availablefrom Sartomer, under trade designation SR368

[0083] TMPTA trimethylolpropane triacrylate, available from Sartomer,under the trade designation SARTOMER 351

[0084] UVI-6990 cationic triaryl sulfonium salt photoinitiator,available from Union Carbide

[0085] V-732 polyamide thermoplastic pellet, having melting point=105°C., available from Creanova, Inc.

[0086] V-4020 a vinyl ether oligomer available from Allied Signal,Morristown, N.J., under the trade designation VECTOMER 4020

Cloth

[0087] Hydro hydroenhanced polyester fabric treated by a processdescribed in U.S. Pat. No. 4,967,456, available from Interspan Divisionof BBA Nonwovens

[0088] KURALON K-II polyvinyl alcohol fill yarns, available from KurarayAmerica, Inc., New York, N.Y., and ring-spun polyester warp yarns,available from Milliken

[0089] PCF filament polyester fill yarns and ring-spun polyester warpyarns, available from Milliken

[0090] PF polyester cloth woven with ring-spun yarns, available fromMilliken

[0091] Y-weight Cotton is 292 g/m² sateen weave Y-weight cotton fabric,available from Milliken

Paper

[0092] D Weight 180 g/m² high tear cylinder paper, available fromFiberMark

[0093] E Weight 220 g/m² high tear cylinder paper, available fromFiberMark

[0094] F Weight 280 g/m² cylinder paper, available from FiberMark, Inc.,Fitchburg, Mass.

[0095] H Weight 400 g/m² paper, available from Aijo Wiggins USA Inc.,Greenwich, Conn.

Nonwoven/Netted Fabrics

[0096] REEMAY 70 g/m² spunbonded polyester mat, available fromTypar/Reemay

[0097] TYPAR 66 g/m² spunbonded polypropylene mat, available fromTypar/Remay

[0098] STABILON 0447 4×4 G-150 fiberglass filaments bonded to 17.5 g/ m²carded polyester mat, available from Milliken

[0099] STABILON 7172 6×6 G-75 fiberglass filaments bonded to 31.5 g/ m²carded polyester mat, available from Milliken

General Preparation of Presized Backings

[0100] A twin screw extruder with six temperature zones, a pellet feedport, a liquid side feed port, and a vacuum port was used. The screw wasstarve fed at speeds of 100 - 250 rpm. The temperature zones range from100 - 140° C. The V-732 was fed to the throat and allowed to melt in thefirst zones. The liquid AMN was injected in the side port and allowed tomix. A 26 inch Hg (87.8 kPa) vacuum was applied to remove undesirablevolatile material.

[0101] The melt was pumped through a 35 centimeter drop die with anadjustable slot. The melt temperature ranged from 105 - 135° C. Thecoating was dropped onto a woven cloth substrate, preferably heated topromote better penetration. The adhesion of the coating was furtherimproved by applying pressure in a heated nip. The coat weight andplacement of the treatment in the cloth was controlled by the extruderthroughput, web speed, roll temperatures and nip pressure. Coat weightsfor cloth presizes were typically in the range of 33 - 167 g/m².

Hand Preparation of Presized Backings

[0102] The components of the presize composition were combined in acontainer and stirred at 125° C. until a uniform melt was obtained.

[0103] The backing material to be coated was laid on the table of aknife coating station, about 6 inches (15.2 centimeters) wide. The knifewas mounted over the backing material and the gap was set toapproximately 3 - 4 mils (0.076 - 0.102 millimeter). Both table andknife heating elements were heated to 125° C. A bead of the moltencomposition was applied to the backing material immediately behind theknife. The backing material was pulled slowly and steadily beneath theknife so as to obtain a uniform coating thickness. The coated backingmaterial was then cured under a bank of two Fusion D UV bulbs set atfull power (600 Watts/inch (236 Watts/centimeter)). The web speed duringUV exposure was typically between 12 to 20 m/min.

General Preparation of Coated Abrasive Articles

[0104] Coated abrasive articles were prepared according to the followingprocedure:

[0105] A presized backing was prepared as described above. A coatablemixture for producing a make coating for the backing was prepared bymixing 64 parts of 75 percent solids phenolic resin (RP1) (48 partsphenolic resin), 52 parts non-agglomerated calcium carbonate filler (dryweight basis), and 4.5 parts water to form a make coating which was 83percent solids, with a wet coating weight of 239 g/m². The make coatingwas applied in each case via roll coating. Next, graded ceramic aluminumoxide particles were electrostatically coated onto the uncured makecoating. Then, the resulting constructions received a precure of 20minutes at 85° C., followed by 70 minutes at 93° C.

[0106] A size coating comprising a conventional resole phenolic resin, afiller, and water was applied over the abrasive particles and the makecoated via a two roll coater. The resulting product was cured of at atemperature of 79° C. for 30 minutes and 88° C. for 75 minutes and thenat 100° C. for 10 hours. The resulting coated abrasive articles weresingle flexed, that is, passed over a one inch diameter (2.54centimeters) roller at an angle of 90° to allow a controlled cracking ofthe make and size coatings. The coated abrasive articles were thenconverted into coated abrasive belts by methods well known in the art.

Test Methods

[0107] 90° Peel Test

[0108] The coated abrasive sheet to be tested was converted into asample about 8 centimeters wide by 25 centimeters long. One-half thelength of a wooden board (17.78 centimeters by 7.62 centimeters by 0.64centimeters thick) was coated with an adhesive. The entire width of, butonly the first 15 centimeters of the length of, the coated abrasivesample was coated with an adhesive on the side bearing the abrasivematerial. The adhesive was 3M JET MELT Adhesive #3779 applied with aPOLYGUN™II glue applicator, both available from Minnesota Mining andManufacturing Co, St. Paul, Minn. Then, the side of the sample bearingthe abrasive material was attached to the side of the board containingthe adhesive coating in such a manner that the 10 centimeters of thecoated abrasive sample not bearing the adhesive overhung from the board.Pressure was applied such that the board and the sample were intimatelybonded, and sufficient time was allowed for the adhesive to cool orharden cure. For samples to be tested at 250° F. (121° C.), a filledphenolic resin as described above under the heading “General Preparationof Coated Abrasive Articles” was used as an adhesive and the adhesivewas cured at 100° C. for about 6 hours.

[0109] Next, the sample to be tested was scored along a straight linesuch that the width of the coated abrasive test specimen was reduced to5.1 centimeters. The resulting coated abrasive sample/board compositewas mounted horizontally in the lower jaw of a tensile testing machinehaving the trade designation SINTECH, and approximately 1 centimeter ofthe overhanging portion of the coated abrasive sample was mounted intothe upper jaw of the machine such that the distance between jaws was10.2 centimeters. The machine separated the jaws at a rate of 0.5cm/sec, with the coated abrasive sample being pulled at an angle of 90°away from the wooden board so that a portion of the sample separatedfrom the board. Separation typically occurs between the cloth treatmentsand the cloth. The machine charted the force per centimeter of specimenwidth required to separate the cloth from the treatment coating. Thehigher the required force, the better adhesion of the treatment coatingto the cloth backing.

[0110] The force required to separate the treatment was expressed inlbF/in width. It is preferred that the force value be at least 16 lbF/in(28 N/cm), more preferably at least 20 lbF/in (35 N/cm) and even morepreferably, at least 30 lbF/in (52.5 N/cm), because inadequate adhesionand weakness at the make coat-backing interface will result in inferiorperformance particularly under high pressure grinding conditions.

Tensile Tests

[0111] The coated abrasive backing or coated abrasive sample to betested was converted into a 2.5 centimeters by 17.8 centimeters strip.The strip was installed between the jaws of a tensile testing machineknown under the trade designation SINTECH so that the jaws wereinitially separated by a space of 0.5 centimeter. The jaws were pulledapart at a rate of 0.5 cm/sec. The machine direction (MD) strips weretaken from the machine direction or the warp direction of the backingsample. The cross direction (CD) strips were taken in the crossdirection of the backing sample. Additionally, the percent stretchdefined as ([final length minus initial length]/initial length) of thesample was measured at a 45 kg load.

Thompson Grinding Test (dry)

[0112] Grade 80 belts were tested on a Thompson Type C12 grindingmachine, available from Waterbury Farrel Technologies, Cheshire, Conn.,using 12.7×17.8 centimeters particleboard (3 workpieces at a time layingon the 17.8 centimeters edge). Coated abrasive material converted to 203centimeters by 6.3 centimeters continuous belts were installed on aThompson grinding machine. The effective cutting area of the abrasivebelt was 2.54 centimeters by 203 centimeters. The workpiece abraded bythese belts was particle board, 2.54 centimeters width by 17.78centimeters length by 10.2 centimeters height. Abrading was conductedalong the 2.54 centimeters by 17.78 centimeters face. The workpiece wasmounted on a reciprocating table. Speed of the abrasive belt was 610surface meters per minute. The table speed, at which the workpiecetraversed, was 30.5 meters per minute. The downfeed was 1.0 millimeterfor the first 1000 passes, then 1.8 millimeters/pass until the belt woreout (determined by loading/burning or high normal forces). The processused was conventional surface grinding wherein the workpiece wasreciprocated beneath the rotating abrasive belt with incrementaldownfeeding between each pass. This grinding was carried out dry. Eachbelt was used until it became loaded or it burned. This test is designedto measure the lifetime of an abrasive belt when the belt is subjectedto a controlled and constant-rate grinding conditions in woodworkingapplications.

Thompson Grinding Test (wet)

[0113] Coated abrasive material converted to 203 centimeters by 7.6centimeters continuous belts were installed on the Thompson grindingmachine. The effective cutting area of the abrasive belt was 2.54centimeters by 203 centimeters. The workpiece abraded by these belts was2.54 centimeters width by 17.78 centimeters length by 10.2 centimetersheight. Abrading was conducted along the 2.54 centimeters by 17.78centimeters face. The workpiece was mounted on a reciprocating table.Speed of the abrasive belt was 610 surface meters per minute. The tablespeed, at which the workpiece traversed, was 7.6 meters per minute. Thedownfeed increment of the abrasive belt was 0.15 millimeter/pass of theworkpiece. The process used was conventional surface grinding whereinthe workpiece was reciprocated beneath the rotating abrasive belt withincremental downfeeding between each pass. This grinding was carried outwet. Each belt was used until it shelled. This test is designed tomeasure the lifetime of an abrasive belt when the belt is subjected towet and constant-rate grinding conditions in metalworking applications.

Pressure Pac Shelling Test

[0114] Endless abrasive belts (7.6 centimeters×335 centimeters) weretested on a constant rate surface grinder by abrading a 1.9 centimetersdiameter face of a 1095 tool steel rod at 5 seconds/rod until the coatedabrasive shelled, that is, a substantial amount of the abrasive gritcame off of the backing. The experimental error of this test was +/−10percent. This test is designed to measure the grinding performance of anabrasive belt when the belt is subjected to severe, high pressuregrinding conditions in metalworking applications.

EXAMPLES 1 - 6

[0115] The effect of average AMN functionality (F) on adhesion wasdetermined. In each case, a 60/40/1.0 V-732/AMN/1-651 ratio was used asa presize coating on PF polyester backing prior to making the abrasiveconstruction. F is defined as the average number of moles ofN-methylolacrylamide/moles of phenol in the AMN. The samples wereprepared using the “hot knife” procedure described above. TABLE 1Example Avg F Adhesion, N/cm 1 0.8 34.2 2 1.3 43.0 3 1.5 54.8 4 1.7 47.05 2.0 47.0 6 2.5 36.2

[0116] The data in Table 1 indicates that an acrylamide/phenol molarratio (F) of 1.5 is preferred.

EXAMPLES 7 - 12

[0117] Samples of several greige polyester cloths supplied by Millikenwere evaluated for stripback adhesion after applying a 60/40/1.0V-732/AMN/I-651 F=1.5, F/P=0.5 hot melt presize. PCF (continuousfilament fill yarns), and KURALON K-II (spun PVA fill yarns) fabricswere coated with the 60/40 V-732/AMN blend described above using hotknife coating equipment, as described above in “General Method of MakingPre-sized Backings”. (F/P is the molar ratio of formaldehyde to phenolcharged in the AMN resin synthesis.) Standard greige PF was coated withthe 60/40 V-732/AMN blend described above as a comparison. Samplepreparation involved first the application of the hot melt presize usingthe “hot knife” procedure described above, followed by following theGeneral Preparation of Coated Abrasives Articles procedure above. Then,the procedure for determining 90° peel was used. Two sets of sampleswere evaluated to determine whether UV dosage has a significant impacton adhesion of the presized backing to the make coat. Results are shownin Tables 2 and 3. TABLE 2 Stripback Adhesion (118 W/cm) ElevatedTemp(250° F.) Room Temp (121° C.) Example Cloth (N/cm) (N/cm) 7 Std PF42.1 35.2 8 PCF 36.2 32.3 9 KURALON 62.6 49.9 K-II

[0118] TABLE 3 Stripback Adhesion (118 W/cm and 157 W/cm) ElevatedTemp(250° F.) Room Temp (121° C.) Example Cloth (N/cm) (N/cm) 10 Std PF42.1 32.3 11 PCF 33.3 30.3 12 KURALON 66.5 64.6 K-II

[0119] The above adhesion values for the KURALON K-II fabric (PVA infill direction) are excellent. The high temperature adhesion (250° F.(121° C.)) is a particularly important characteristic of utilizing thehot melt composition of the invention as a presize on fabric for acoated abrasive article requiring high heat resistance.

EXAMPLES 13 - 16 and Comparative Examples A - B

[0120] The coated abrasive belts for Examples 13 - 16 and ComparativeExamples A and B were made according to the General Procedure for MakingCoated Abrasives above. The cloth backings of Examples 13 - 16 werepresized with 175 g/m² 60/40/1.5 V-732/AMN 1.5/1- 651 in hot melt formusing an extruder and subsequently backsized with 145 g/m² 67/33/1.0RP2/PETA/I- 651 at room temperature in the form of a 75 percent solidsaqueous solution. The backings of Comparative Examples A - B weresaturated with a 44 percent aqueous phenolic/latex solution(85.5/9.5/3.33/1.67 RP2/Hycar 1581/FE203/CB), presized with a 52 percentsolids aqueous phenolic/latex solution (90/10 RP3/Hycar 1581, andbacksized with a 72 percent aqueous phenolic/latex solution(43/55/1.78/0.22 RP3/CaCO3/FE203/CB).

[0121] The make coating for Examples 13 - 16 and Comparative Examples Aand B was 239 g/m² (wet) of 64 parts RP1, 52 parts calcium carbonate,and 4.5 parts water. The mineral was of 612 g/m² 50 (ANSI standardB74.18). The size coating was about 285 g/m² (wet) 42 parts RP1, 68parts cryolite, and 12 parts water. Examples 13 - 16 were tested forgrinding performance under dry and wet conditions. The results are shownin Tables 4 and 5. TABLE 4 Pressure Pac Shelling Test Avg # LotTreatment Cloth Bars % Comparative A Comparative A Phenolic PF 33 100 Example 13 60/40 PF 29 88 V-732/AMN Example 14 60/40 HYDRO 30 91V-732/AMN

[0122] TABLE 5 Wet Thompson, Shelling Endpoint Avg Cut Lot TreatmentCloth (g) % Comparative B Comparative B Phenolic PF 1600 100 Example 1560/40 PF 2290 143 V-732/AMN Example 16 60/40 HYDRO 2649 166 V-732/AMN

[0123] The treated backings of the invention provided comparableperformance under dry conditions, and superior performance under wetconditions.

EXAMPLE 17 and Comparative Example C

[0124] Both polyester cloths were presized with the 60/40/1.0 V-751/AMN1.5/I-651 hot melt presize described above using an extruder andbacksized with RP2/PETA/I-651 described above. Then the grade 50 (metalgrinding) coated abrasive articles were made as described above inExamples 13 - 16. Test evaluation data is in Table 6. TABLE 6 PressurePac Shelling Test: Dry, constant rate (7.6 × 335 centimeters belt)Example Backing # Bars Description Type Cut % Comparative C ComparativeC PF 35 100 Example 17 HYDRO 55 157

[0125] The metal grinding performance of Example 17 (using hydroenhancedcloth) of the invention is superior to that of Comparative Example C.

EXAMPLE 18 - 24

[0126] A multilayer or laminate backing was prepared for Examples 18 -24 by first coating E Weight paper with from 63-418 g/m² (depending onthe choice of the second substrate) of a 60/40/1.5 V-732/AMN 2.0/I-651hot melt composition (Coating in Table 7). The materials were compoundedas described above in Examples 13 - 17, or pre-compounded elsewhere andfed as a single stream into a single screw extruder. The coated paperwas then bonded to a nonwoven material as indicated in Tables 7 and 8.The samples were then compressed between at least one set of heated niprolls. The backing constructions were then cured under two FUSION D UVbulbs (600 W/in) at a rate of 50 feet/min (15.2 m/min).

[0127] The make coat, mineral, and size coat for Examples 18 - 24 andComparative Examples D - G was make coat: 64 parts of a resole phenolicresin (RP-1) (48 parts dry phenolic resin), 52 parts calcium carbonatefiller (dry weight basis), and 4.5 parts water, with a wet coatingweight of 105 g/m²; mineral: grade 80 (ANSI standard B74.18) with acoating weight of 231 g/m²; and size coat: 99 parts RP1, 26 partscalcium carbonate and titanium dioxide fillers (dry weight basis), and14 parts water, with a wet coating weight of about 138 g/m². Examples18 - 24 and Comparative Examples D - H then received a thermal cure of30 minutes at 79° C. plus 75 minutes at 88° C. followed by 10 hours at100° C. Examples 21 - 23 are of the same construction as Examples 18 -20, respectively.

[0128] The following physical properties were measured on the coatedlaminate backings. In each column, MD means machine direction, and CDmeans cross direction. TABLE 7 Room Temperature Tensile Data Tensiles %Stretch (N/cm, (LbF/in)) (at break) Backing Material (MD/CD) (MD/CD)Construction Example 18 264, 142 2.6, 6.2 E Weight (151), (81)Paper/Coating TYPAR Example 19 208, 82 2.6, 1.9 E Weight (119), (46.9)Paper/Coating/ STABILON 0447 Example 20 268, 113 2.0, 2.2 E Weight(153), (64.8) Paper/Coating Comparative D 415, 175.1 2.2, 6.2 H Weight(237), (100) Paper Comparative E 502, 186 5.2, 11.7 Y Weight (287),(106) Cotton

[0129] TABLE 8 Elevated Temperature (250° F.) Tensile Data Tensiles %Stretch (N/cm, (LbF/in)) (at break) Backing Material (MD/CD) (MD/CD)Construction Example 21 142, 77 2.2, 5.4 E Weight (81), (44.1)Paper/Coating/ TYPAR Example 22 169, 80 2.5, 2.6 E Weight (96.7), (45.8)Paper/Coating/ STABILON 0447 Example 23 128, 60 2.0, 4.1 E Weight(73.2), (34.1) Paper/Coating Comparative F 243, 111 1.5, 1.9 H Weight(139), (63.7) Paper Comparative G 245, 104 3.6, 11.6 Y Weight (140),(59.2) Cotton

[0130] The Comparative H belt was Grade commercially available Grade 803M XODUST 970 DZ and the Example 24 belt was made as in Examples 19 and22. Table 9 lists data from the Thompson dry particle board test onbelts of Comparative H and Example 24. TABLE 9 Backing Passes at BeltConstruction 1.8 mm Fn(N) Comparative H Y weight cotton 160 356 7801334  Example 24 E Weight 160 271 Paper/Coating/STABI 800 302 LON 04472387  1312 

[0131] Both Example 24 and Comparative Example H achieved a similarburning/loading endpoint.

EXAMPLES 25 and 26

[0132] Examples 25 and 26 are coated abrasive samples and were preparedaccording to the Hand Preparation of Presize Backings and the GeneralPreparation of Coated Abrasive Articles. The presize coatingcompositions were 20/20/60 AMN/AMPNV-732 (Example 25) and 30/30/40AMN/AMPNV-732 (Example 26). Both compositions were coated on PFpolyester cloth. The F/P ratio and the average acrylamide functionalityper aromatic ring of the AMN were 0.35 and 0.8, respectively. Thehandspread samples were tested for Stripback Adhesion, described above.Example 25 had RT and ET stripback adhesion values of 32 N/cm and 37.5N/cm. Example 26 had RT and ET stripback adhesion values of 25.4 N/cmand 27.5 N/cm.

EXAMPLES 27 - 31

[0133] Table 10 shows the presize compositions for Examples 27 - 30 andComparative Examples I - L. The composition shown for Example 31 andComparative Example M is for a backsize. The backing used in theExamples was hydroenhanced polyester cloth (PF). The backing used in theComparative Examples was polyester cloth (PF).

[0134] Examples 27 - 30 and Comparative Examples I - L were presizedusing a Mayer rod draw down coating method. Example 31 and ComparativeExample M were saturated with a composition containing: 59.1 percentRP-2, 10.9 percent H-1581, and 30 percent water, using a conventionaldip and squeeze method and the backsize was applied by a conventionalknife coating method. TABLE 10 Example Example Example Example Example27; 28; 29; 30; 31; CE I CE J CE K CE L CE M Component (wt %) (wt %) (wt%) (wt %) (wt %) EP-1 53.5 61.8 V-4020 35.6 TMPTA 50.0 TATHEIC 50.0NR-9030 53.5 H-1581 46.5 E-826 33.2 RP-2 42.1 DVE-3 8.9 CD-1010 2.0I-369 1.0 2- 5.0 ethoxy- ethanol (solvent) CaCO₃ 48.0 Water 9.9

[0135] The coated side of each sample above was cured as follows:

[0136] Example 27 and Comparative 1: 2 UV passes @ 7.6m/min, 157W/cm,+15 min, 90° C.

[0137] Example 28 and Comparative J: 2 UV passes @ 7.6m/min, 157 W/cm

[0138] Example 29 and Comparative K: 15 min, 90° C.

[0139] Example 30 and Comparative L: 3 min, 100° C.

[0140] Example 31 and Comparative M: 3 min, 110° C. for both coatings

[0141] Each UV pass was beneath a bank of 2 medium pressure Hg vaporlamps, American Ultraviolet Co., Murray Hill, N.J.

[0142] Table 11 shows the backing type and the dry coating weights ofthe above Examples and Comparative Examples. TABLE 11 Dry Coating WeightSample Cloth (g/m²) Example 27 Hydro PF 136 Comparative Example I PF 135Example 28 Hydro PF 152 Comparative Example J PF 168 Example 29 Hydro PF110 Comparative Example K PF 110 Example 30 Hydro PF 150 ComparativeExample L PF 150 Example 31 Hydro PF 187 Comparative Example M PF 150

[0143] Table 12 shows the 90 Degree Peel Adhesion (at 21° C.) resultsfor the above Examples and Comparative Examples. TABLE 12 Peel AdhesionSAMPLE (N/cm) Example 27 30.8 Comparative Example I 28.9 Example 28 30.6Comparative Example J 16.1 Example 29 36.2 Comparative Example K 27.3Example 30 56.9 Comparative Example L 38.0 Example 31 66.8 ComparativeExample M 32.9

[0144] The above data show that hydroenhanced backings provide anadhesion performance advantage for a variety of cloth treatmentcompositions.

[0145] Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from thescope and spirit of this invention, and it should be understood thatthis invention is not to be unduly limited to the illustrativeembodiments set forth herein.

What is claimed is:
 1. A substrate for an abrasive article comprising:a) a backing; and b) a crosslinked treatment coat on said backing, saidtreatment coat is formed from a curable precursor composition comprisinga mixture of: i) from about 30 to about 60 weight percent of anoligomeric aminoplast resin having on average at least one pendantα,β-unsaturated carbonyl group per oligomeric unit, ii) from about 70 toabout 40 weight percent of a thermoplastic polyamide miscible in saidaminoplast resin, the weight percents being based on the total resincontent, and iii) a sufficient amount of a catalyst for the curableoligomeric aminoplast resin having on average at least one pendantα,β-unsaturated carbonyl group per oligomeric unit, said catalyst beingstable at a temperature of mixing of the components.
 2. The substrate ofclaim 1 , wherein the thermoplastic polyamide has a melting point offrom about 95° C. to about 150° C. as measured by DSC.
 3. The substrateof claim 1 , wherein the backing is constructed from cloth comprisingvulcanized fiber, paper, nonwoven materials, fibrous reinforcedthermoplastic materials, polymeric films, metal foils, foams, ortransfer coated multilayer combinations thereof.
 4. The substrate ofclaim 3 , wherein the cloth backing comprises fibers selected from thegroup consisting of cotton, polyester, rayon, lyocell, silk, polyamide,and combinations thereof.
 5. The substrate of claim 1 , wherein theoligomeric aminoplast resin having on average at least one pendantα,β-unsaturated carbonyl group per oligomeric unit is anacrylamidomethyl-novolak resin.
 6. The substrate of claim 5 , whereinthe acrylamidomethyl-novolak resin has an average acrylamidefunctionality of from 0.8 to 2.5 acrylamide groups per aromatic ring. 7.The substrate of claim 1 , wherein the backing is comprised of two ormore backing layers bonded together by said crosslinked treatment coat.8. The substrate of claim 7 , wherein at least one of the layers is madefrom paper.
 9. The substrate of claim 3 , wherein the cloth backingcomprises continuous filament polymer yarns.
 10. The substrate of claim1 , wherein the backing comprises a hydroenhanced cloth.
 11. Thesubstrate of claim 3 , wherein the cloth backing comprises polyvinylalcohol yams.
 12. The substrate of claim 1 , wherein the catalyst is aphotocatalyst.
 13. A curable precursor composition comprising: a) fromabout 30 to about 60 weight percent of an oligomeric aminoplast resinhaving on average at least one pendant α,β-unsaturated carbonyl groupper oligomeric unit; b) from about 70 to about 40 weight percent of athermoplastic polyamide miscible in said aminoplast resin, the weightpercents being based on the total resin content; and c) a sufficientamount of a catalyst for the curable oligomeric aminoplast resin havingon average at least one pendant α,β-unsaturated carbonyl group peroligomeric unit, said catalyst being stable at temperature of mixing ofthe components.
 14. The composition of claim 13 , wherein thethermoplastic polyamide has a melting point in the range of from about95° C. to about 150° C. as measured by DSC.
 15. The composition of claim13 , wherein the thermoplastic polyamide has a melt flow rate of from 10to 90 g/10 min at 160° C.
 16. The composition of claim 13 , wherein thecatalyst is a photocatalyst.
 17. The composition of claim 13 , whereinthe composition is a molten mixture or a melt-processable solid.
 18. Thecomposition of claim 13 , wherein the oligomeric aminoplast resin havingon average at least one pendant α,β-unsaturated carbonyl group peroligomeric unit is an acrylamidomethyl-novolak resin.
 19. Thecomposition of claim 13 further comprising acrylamidomethyl-phenol. 20.A composite backing comprising: a) a first backing layer; b) a secondbacking layer; and c) a cured composition bonding said first and secondsubstrates together to form a composite backing, the cured compositioncomprising the reaction product of a mixture of: i) from about 30 toabout 60 weight percent of an oligomeric aminoplast resin having onaverage at least one pendant α,β-unsaturated carbonyl group peroligomeric unit, ii) from about 70 to about 40 weight percent of athermoplastic polyamide miscible in said aminoplast resin, the weightpercents being based on the total resin content, and iii) a sufficientamount of a catalyst for the curable oligomeric aminoplast resin havingon average at least one pendant α,β-unsaturated carbonyl group peroligomeric unit, said catalyst being stable at a temperature of mixingof the components.
 21. A substrate for an abrasive article comprising:a) a backing comprising hydroenhanced cloth; and b) a treatment coat onsaid backing.
 22. The backing of claim 21 wherein said treatment coat isa composition comprising thermoset resins, thermoplastic resins, orcombinations thereof.
 23. The substrate of claim 21 wherein saidtreatment coat is a composition comprising resins selected from thegroup consisting of phenolic resins, novolak resins, nitrile latexresins, aminoplast resins having pendant, α,β-unsaturated carbonylgroups, urethane resins, epoxy resins, urea-aldehyde resins,isocyanurate resins, melamine-aldehyde resins, acrylate resins,acrylated isocyanurate resins, acrylated urethane resins, acrylatedepoxy resins, bismaleimide resins, polyester resins, aminoplastresin/thermoplastic polyamide blends as described herein, acrylatedoligomer/thermoplastic polyamide blends and mixtures thereof
 24. Thesubstrate of claim 21 wherein the hydroenhanced cloth comprises yarnsmade from resins selected from the group consisting of polyester,cotton, rayon polycotton yarns, and combinations thereof.
 25. Thesubstrate of claim 21 wherein the hydroenhanced cloth comprises yarnsmade from polyester.